Subterranean debris removal devices have been available in many forms. Different designs are targets at different sized debris. In the area of removal of sand and other particulates an eductor design offered by Baker Hughes Inc. under the name VACS features an eductor to draw debris laden fluid into an inlet tube that is surrounded by a housing to define the debris collection chamber. The debris laden flow makes side exits under an inverted cone cover where the idea is that the fluid stream is redirected back downhole followed by a turn to go back uphole so that the solids will be directed down into the annular collection volume and the remaining fluid stream will get drawn up by the eductor through a screen. This design is illustrated in U.S. Pat. No. 7,472,745 FIG. 1 showing the flow stream 32 making a turn to go through a screen 34 while the debris is supposed to drop into the annular volume 38. While this design does an admirable job with the larger particles it has been known on occasion to pass the finer particles with a result of flow interruptions as the screen clogs. Designs have been proposed to clear the screen by reversing flow direction through it or by providing signaling capabilities to indicate the flow through the device in real time. The basic design of the fluid stream through the device has remained unchanged for the most part until a recent development described below.
Referring to FIG. 1 a housing 10 has a debris inlet tube 12 that defines an annularly shaped debris collection volume 14. Debris laden flow exits the top 16 of the inlet tube 12 and hits the curved wall 18 for a reversal in the flow direction. The flow makes a 180 degree turn and goes in the downhole direction between parallel plates 20 and 22 that are in contact with the inlet tube 12 to define parallel passages 24 and 26 that extend to lower ends 28 and 30 of plates 20 and 22 respectively. Plates 20 and 22 define gaps between themselves and the inside wall of the housing 10 that represent another 180 degree turn for the debris laden fluid with the idea that the debris will separate into annular space 14 as the fluid drawn by an eductor as is used in the VACS system described above passes through a screen that is not shown and into the eductor inlet. The passages 24 and 26 are discrete along the outside of the inlet tube 12 until the lower ends 28 and 30 of the plates 20 and 22 are reached. At that point the fluid flow turns 180 degrees from passages 26 and 28 and commingles for the passage up the outer passages that are formed between the plates 20 and 22 and the inside wall of the housing 10.
While this design was an improvement over the separation capability of the design shown as FIG. 1 of U.S. Pat. No. 7,472,745 there were several issues with this design that limited its debris separation capability. The sharp radius bends that were required to transition from downhole direction of flow in passages 24 and 26 to the exit passage between the plates and the inside wall of the housing 10 caused wide flow streams to be formed that would not easily release the lighter weight solids that would have to cross the width of the flowing stream as that stream made an abrupt 180 degree short radius turn. Further the returning stream going uphole after making the second 180 degree turn would run up against the downhole oriented debris laden stream coming down passages 24 and 26 with the resulting turbulence of such opposed flows carrying off incoming debris from the passages 26 and 28 and carry such debris up to the screen and potentially clog the screen.
What was needed was to provide a better separator of solids from liquids in a confined space where the improved separation could rise to the level of omitting the screen shown in U.S. Pat. No. 7,472,745 FIG. 1. This has been accomplished with the present invention that has taken the FIG. 1 design and made improvements to add a pair of extending tabs from diagonally opposed corners at the lower ends of the parallel plates. The downhole flow can now cross over to go up without encountering the downhole oriented flow still coming down. The ability to cross over also makes for a larger radius of the flow stream and for a thinner stream to better allow solids to pass though the narrower width to be collected in the annular receptacle at the housing bottom. The same happens in mirror image on the other side due to the extending straight tabs. Alternatively one or a pair of diagonally opposed tabs with curvature can be used to operate on similar principles. These and other features of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiments and the associated drawings while understanding that the full scope of the invention is to be found in the appended claims.